Abstract

The effectiveness of DARAMEND bioremediation was demonstrated at pilot-scale on two separate sites in Canada. The first site (Pacific Place, BC) involved the treatment of 100 tons of soil excavated from a former Pintsch oil gasification plant and the second site (Hamilton Harbour, Ontario) involved the treatment of 150 tons of sediment impacted from coal coking operations for the steel manufacturing industry.

The technology used involved solid phase aerobic bioremediation utilizing indigenous microorganisms in a prepared bed (land treatment). The technology involves the addition of nutrients and proprietary organic amendments to optimize the rate of microbial activity in the soil/sediment. The technology also requires control of the soil moisture content and aeration through irrigation and till-age.

The initial total PAH concentration at the first site was 659 mg/kg. After ten months of treatment, the concentrations were reduced to 106 mg/kg, well below the specified 200 mg/kg target for that site. Benzo(a)pyrene, often considered the most recalcitrant PAH, was reduced from an initial concentration of 47 mg/kg to 12 mg/kg over the same period.

Prior to initiation of treatment dredged sediment at the second site was allowed to passively de-water within the bioremediation cell. Total PAH concentrations at this site were reduced from 1139 mg/kg initially to 110 mg/kg after 312 days of treatment. With the exception of benzo(a)pyrene the concentration of all regulated PAHs was reduced to below guidelines after 245 days of treatment. Benzo(a)pyrene required 312 days of treatment before the remedial guideline was reached.

Key words: aerobic, benzo(a)pyrene, bioremediation, cost, Daramend, polycyclic aromatic hydrocarbon, sediment, soil